import fs from 'file-saver'
import * as XLSX from 'xlsx';
// import xlsx from 'xlsx'


export function xlsx(json, fields, filename = '.xlsx') {//导出xlsx
  json.forEach(item => {
    for (let i in item) {
      if (fields.hasOwnProperty(i)) {
        item[fields[i]] = item[i];
      }
      delete item[i]; //删除原先的对象属性
    }
  })
  let sheetName = filename //excel的文件名称
  let wb = XLSX.utils.book_new()  //工作簿对象包含一SheetNames数组，以及一个表对象映射表名称到表对象。XLSX.utils.book_new实用函数创建一个新的工作簿对象。
  let ws = XLSX.utils.json_to_sheet(json, { header: Object.values(fields) }) //将JS对象数组转换为工作表。
  wb.SheetNames.push(sheetName)
  wb.Sheets[sheetName] = ws
  const defaultCellStyle = { font: { name: "Verdana", sz: 13, color: "FF00FF88" }, fill: { fgColor: { rgb: "FFFFAA00" } } };//设置表格的样式
  let wopts = { bookType: 'xlsx', bookSST: false, type: 'binary', cellStyles: true, defaultCellStyle: defaultCellStyle, showGridLines: false }  //写入的样式
  let wbout = XLSX.write(wb, wopts)
  let blob = new Blob([s2ab(wbout)], { type: 'application/octet-stream' })
  fs.saveAs(blob, filename + '.xlsx')
}

const s2ab = s => {
  var buf;
  if (typeof ArrayBuffer !== 'undefined') {
    buf = new ArrayBuffer(s.length)
    var view = new Uint8Array(buf)
    for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xff
    return buf
  } else {
    buf = new Array(s.length);
    for (var i = 0; i != s.length; ++i) buf[i] = s.charCodeAt(i) & 0xFF;
    return buf;
  }
}

